Method and means for deflashinc or trimming molder rubber parts



A ril 14, 1964 M. LELIAERT 25,554

METHOD AND MEANS FOR DEIF'LASHINC 0R TRIMMING MOLDER RUBBER PARTS 2Sheets-Sheet 1 Original Filed July- 29, 1959 frwerzior .QamonoIMleZzaeri 9 A ril 14, 1964 R. M. LELIAERT Re- 25554 METHOD ANDMEANS FOR DEFLASHING OR TRIMMING MOLDER RUBBER PARTS Original Filed July29, 1959 2 heets-Sheet 2 Fiat 3 12 EaymondMZeZz'aen': F 4 [warrior 2y0m, v/m/ ail" United States Patent Ofilice Re. 25,554 Reissued Apr. 14,1964 25,554 METHGD AND MEANS FGR DEFLASHING OR TRIMMING MOLDER RUBBERPARTS Raymond lvl. Leliaert, outh Bend, Ind, assignor, by

mesne assignments, to Bell Intercontinental Corporation, South Bend,Ind, a corporation of Delaware Original No. 2,996,846, dated Aug. 22,1961, Ser. No.

330,393, July 29, 1959. Application for reissue Aug. 27, 1963, Ser. No.305,247

13 Claims. (CI. 5113) Matter enclosed in heavy brackets [1 appears inthe original patent but forms no part of this reissue specification;matter printed in italics indicates the additions made by reissue.

This invention relates to methods and means for removing fiashings andfins or the like or otherwise trimming molded rubber parts; and moreparticularly to improvements in methods and machines for such purposesusing the technique of first freezing the parts so as to render theflash or fins brittle and therefore susceptible to a flashing or finremoving operation.

Previously, rubber molded parts have in some cases been subjected toconventional freezing and tumbling barrel type processes with a view tothereby knocking off the embrittled fins and fiashings; but in manycases without satisfactory results, depending upon the nature of theworkpieces being operated upon. For example, in many cases theworkpieces include certain areas which are not accessible to theabrasive action of a conventional tumbling barrel operation. This isbecause in connection with a tumbling process the abrasive media must beof certain size and mass to be effective, and often the media would thenbe too large to satisfactorily remove flash and fins from certain areasof complex shaped parts. Furthermore, tumbling barrel techniques asapplied to frozen rubber parts for defiashing purposes usually result infreezing throughout of the rubber parts, because of the length of timerequired to completely deflash by tumbling methods. Thus, such methodsinvolve the disadvantages of unnecessarily expensive freezing gasconsumption and machine time, and incidental development of stresscracks or other damage elfects in the frozen parts. Many types of moldedrubber parts are not adapted to be processed by conventionalfreeze-tumbling methods, because such methods usually embrittle andrender relatively fragile certain portions of the parts such asprojecting portions and edge portions of the workpieces therebysubjecting them to unwanted abrading and chipping ofi, or the like.Thus, it will be appreciated that conventional freeze-tumblingoperations on frozen molded rubber parts for definning and deflashingpur poses or the like are in many cases totally impracticable anduseless.

It is an object of the present invention to provide a novel method andapparatus for differentially freezing the flashing or fin and main bodyportions of molded rubber parts; to handle such parts in novel andimproved manner during the operation; and to subject the parts to anovel and improved abrading operating gaining access to heretoforeinaccessible portions of the parts, and removing flash and fin portionscompletely and cleanly without damage to other portions of the rubberparts.

Another object is to provide an improved method and apparatus asaforesaid which will broaden the practical scope of application of thefreeze-definning and defiashing technique, and which will be operableupon parts which previously, due to their design and construction, werenot susceptible to freeze-tumbling methods and therefore werenecessarily finished by relatively expensive individual hand operations.

Another object of the present invention is to provide an improved methodand apparatus as aforesaid which is more economical in its use of thefreezing media, compared to processes of the prior art, wherebysubstantial economies in the overall operation are effected.

Another object is to provide an improved method as aforesaid which isoperable with increased speed and whereby improved utilization of theequipment and higher output rates and economies in the use of attendantlabor are effected.

Other objects and advantages will appear from the specificationhereinafter.

Generally stated, the present invention contemplates an operatingtechnique involving flash-freezing of the molded rubber parts to bedefinned or deflashed, etc., so that preferably only the relatively thinflashing or fin portions or the like extending from the parts becomeembrittled, while the molded body parts remain substantially unfrozen;and then projecting against the parts an airless blast or abrasive mediamoving at such velocity as to break off the hardened brittle fins orflashings, but not at such velocity as to cause rounding of the edges orother damage to other portions of the workpieces. During this operationin some cases the workpieces will be constantly turned, but in othercases they may be otherwise disposed and conveyed in their frozen statewhile the abrasive blast directing devices are arranged to project theabrasive media against and into all desired portions of the workpieces.The abrasive media is selected as to size so as to be adapted to readilygain access into recessed portions of the workpieces, such as would notbe reached in conventional freeze-tumbling operations or the like.

Furthermore, the invention contemplates, generally, provision of anapparatus such as will be adapted to relatively quickly differentiallyfreeze the undesirable flash or fin portions of the workpieces withoutsubstantial freezing of the relatively thicker body parts; presentingthe differentially frozen workpieces to abrasive media airless blasts,

while presenting the workpieces to expose the desired portions thereof;abstracting from the operation the finer flash and fin pieces as well asthe spent abrasive media, and separating from the mixture any reusableabrasive media; and returning it to the blasting operation withoutsubstantial inlet of relatively warm and/ or moisture laden atmosphere.By way of one example of performance of the method of the invention, andof an apparatus by which the invention may be practiced, a machineconstructed in accord therewith is illustrated by the accompanyingdrawings wherein:

FIG. 1 is a schematic illustration, in the form of a compositeelevational-sectional view, of an apparatus constructed in accord withthe present invention;

FIG. 2 is a fragmentary section taken along line 11-11 of FIG. 1;

FIG. 3 is an enlarged detail, partly in section, of a portion of FIG. 1;and

FIG. 4 schematically illustrates a mode of operation of the inventionupon a typically shaped workpiece.

As shown in the accompanying drawing, the apparatus.

is arranged to perform definning or defiashing operations upon batchesof molded rubber articles such as are indicated generally in FIG. 1 at10. A sectional view on an enlarged scale, of a typical workpiece isalso shown at FIG. 4. The workpieces are shown herein as being supportedupon an endless apron type conveyor designated generally at 12, which isin the form of an endless belt training around pulleys or rollers 14,16, and a driven pulley or sprockets 15, and so arranged that the upperstrand of the conveyor device trains under and behind a pair of spacedbarrel heads 1818 which are carried on shafts 2020. Thus, as the barrelheads rotate, the endless belt is guided thereby in its travel, thuscausing it to assume a pocket type formation into which the workpieces10 are cradled. This conveyor is of the 3 type disclosed for example inUS. Patents 1,567,077; 1,882,443; and 2,104,055. However, it is to beunderstood that any other suitable type conveyor may be used in lieuthereof.

A loading chute as indicated at 22 is provided to facilitate loading ofconsecutive batches of workpieces into the deflashing chamber, and innormal operation the conveyor is driven so that the top strand portionthereof moves continuously inwardly and then upwardly toward the pulleys15. Thus, in this case the workpieces are continuously drawn by theconveyor inwardly and then upwardly until such time as they gently turnover and away from the vertical climb portions. Cleats or the like asindicated at 24 are preferably provided in some cases on the conveyor tofacilitate turning over of the workpieces as the conveyor operates. Anunloading chute as indicated at 27 is also provided to receive thefinished workpieces whenever a batch is completed and the conveyor isreversed in its direction of operation.

More specifically, the construction of the conveyor 12 may be of anypreferred form, but by way of an example it may comprise a speciallycompounded abrasive-resistant rubber or plastic material adapted toremain flexible under sub-zero temperature conditions. Or, it may be ofan apron conveyor type, comprising articulated slats or aprons formed ofmetal or the like. As shown herein the conveyor device is enclosedwithin a housing 25 which conveniently mounts one or more abrasive madiaprojecting machines such as are indicated generally at 26 in thedrawing. The abrasive blast projecting machines may be of any suitabletype, and for example may be of the type disclosed in US. Patent No.2,708,814.

In any case, the blast machine or machines 26 will of course be powerdriven as indicated at 28 (FIG. 2) and arranged to direct by airlessblast techniques, streams or patterns of steel shot or other abrasivematerials, as explained hereinafter, directly downwardly into thehousing 25 between the barrel heads 1818 so as to strike against theworkpieces which are cradled in the conveyor device. Thus as shown inFIGS. 1, 2, 4 the blast machine or machines 26 will be arranged to throwthe blast media against the workpieces in the form of patterns orstreams, as indicated at 30. The blast machines '26 are arranged to besupplied continuously with blasting media, as through an abrasivestorage hopper 32, as will be explained more fully hereinafter.

The workpiece support conveyor 12 is of perforate form to permit passagetherethrough of spent abrasive media and small particles of fins or.flashings such as have become detached from the workpieces duringoperation of the device. For this purpose, the conveyor device may beformed with drain holes therethrough, or may be otherwise constructed inany preferred manner so as to provide interstices through which thespent abrasive and smaller refuse parts from the operation may escapedownwardly into a collection hopper 34 as shown in FIG. 1. The refuse isfed by gravity from the hopper 34 into the boot portion 37 of a bucketelevator as indicated at 38; the elevator 38 being arranged to deliverthe mixture of rubber refuse and worn out abrasive and reusable abrasivemedia into a separator device as indicated generally at 40.

The separator mechanism may be of any preferred form, and may include arotary screen as indicated at 41 and/ or an air separator. In any caseit will be arranged so as to discharge, as indicated at 42, the trashcomponents of the feed mixture comprising non-reusable portions of theabrasive media and the rubber fins or flash particles previously removedfrom the workpieces. The reusable abrasive is then fed by gravitythrough a chute portion 44 into the abrasive storage hopper 32 whichfeeds the blast machine as explained hereinabove. A dust collectorhaving its suction intake duct as indicated at 46 connected incommunication with the interior of the elevator casing and with theinterior of the separator casing, is provided for the purpose ofconstantly eliminating dust accumulations from the device, and formaintaining the atmosphere internally of the housing 25 under slightlyreduced pressure from that externally thereof as contained within casing75. This, in combination with other features to be described later,account for an improved operation as will be more fully explainedhereinafter.

To freeze the workpieces any suitable arrangement may be employed. Forexample, the workpieces may be frozen prior to being delivered intooperative position upon the conveyor as by passing them through asuitably chilled chamber, or by spraying them with a cooling fluid, orby mixing them with particles of Dry Ice, or by dipping them into a coldliquid bath, or the like. I prefer however to freeze the workpiecesfollowing delivery thereof into the machine; and in such case thefreezing operation may be performed for example by mixing Dry Iceparticles into the workpiece load on the conveyor, with each new batchof workpieces as delivered to the machine. However, a more satisfactoryand convenient method is illustrated in the drawing herewith andcomprises use of a pipe manifold as indicated at 50 which is providedwith a series of branch pipes 51 carrying spray nozzles 52 projectinginto the housing 25. The manifold 50 is arranged to be connected througha control valve 54 to a source of liquid carbon dioxide as indicated at5'5 (FIG. 2).

Thus, the nozzles 52 are arranged to spray expanding gas from the liquidcarbon dioxide supply over the full width of the workpiece load whilethe latter is being rotated and turned by means of the conveyor device.Regulation of the valve 54 and of the diameters of the orifices in thenozzles 52 Will of course reguiate the rate of freezing of theworkpieces, so as to provide optimum results as will be more evidenthereinafter. Thus the device may be arranged so as to introduce into thehousing 25 carbon dioxide gas which will act to quick-freeze therelatively thin flashing and fin portions of the load of workpiecesrather quickly, before the thicker body portions thereof become frozen.Operation of the blast media upon the workpieces will then quickly andneatly remove the brittle fins and flashing portions, the finerparticles of which filter down through the conveyor drain holes alongwith the spent abrasive media particles, into the collection hopper 34as explained hereinabove. Throughout this phase of the operation theagitator bars as indicated at 24 act to cause the workpieces to slowlyturn over and thus to present constantly changing facets of theworkpieces to the blast operation, thereby insuring penetration ofheretofore inaccessible portions of complex shaped workpieces, asexplained hereinabove.

It is a particular feature of the present invention that the processthereof is operable to treat complex-shaped parts such as heretoforerequire individual hand process ing. For example, a workpiece such as issectionally illustrated at FIG. 4 may be readily processed in accordwith the present invention, although it would be impossible or extremelydifficult to satisfactorily handle it in connection with a freeze-tumblebarrel type operation. In this case the relatively fragile lip portion60 as Well as flange 61 must be protected against damage while theadjacent flash portion 62 is to be removed. Similarly, the outer flashportion 64 must be removed from the workpiece without rounding off ofthe corners thereof. Conventional tumbling barrel operations onworkpieces of this nature would result in damage to the relativelyfragile flange and lip portions; and unsatisfactory and perhaps onlypartial removal of the objectional fin or flash portions. On the otherhand in accord with the present invention, the relatively brittle, thinportions of the workpiece are attacked from a multitude of directions,due to the multiple angular pattern of media projected and reboundthereof following initial impact against the work. Thus in the case ofthe present invention the brittle flash portions are quickly and cleanlysevered from the workpieces by a media gaining access to all surfacesthereof. At the same time, in the case of the present invention thereare no damaging impacts of relatively larger abrasion particles such aswood blocks, steel diagonals, etc. as used in barrel tumbling, againstthe workpieces such as would deform the lip and flange portions of theworkpiece as shown in FIG. 4, which are intended to remain intact.

To facilitate proper functioning of the apparatus in accord with thepresent invention, it will of course be understood that the housing 25will be provided with removable inlet and outlet doorways in conjunctionwith the inlet and delivery chutes 22, 27, so as to normally maintainthe housing in substantially air-sealed relation to maintain thetemperature thereof uniformly at the de' sired reduced temperature. Tofurther facilitate this phase of the operation, the abrasive media feedspout as indicated at 70 which feeds the blast machine 26, may beprovided with an orifice plate as indicated at 72 (FIG. 3) which servesto meter the abrasive media to be thrown by the blast, and also servesto minimize the pumping of air through the blasting machine into theinterior of the housing 25. Use of airless blast machines as indicatedat 26 also contributes to the success of the system because they involveno incidental circulation of air which might interfere with efficientcooling of the workpieces.

Also, to facilitate performance of the apparatus, it is enclosed withina substantially air-tight and thermalinsulated casing as indicatedgenerally at 75 (FIG. 1). Thus, the housing 25, the media projectionmachine 26, the elevator 38, the separator 40, and the dust collectorunit 45 are all confined within a heat-insulated and substantiallyatmospheric-sealed casing. This serves to maintain a sub-ambienttemperature in the area of the blast operation which operates to reducethe cooling gas consumption requirement and permits recirculation of thecold gases discharged by the dust collector. Also because the casing iskept at an internal pressure somewhat greater than the atmosphericpressure externally thereof due to the expansion of the liquid carbondioxide through nozzles 52, moisture laden air from externally of theapparatus is prevented from gaining access thereinto. This minimizes theproblem of condensation within the mill such as would otherwise bedetrimental to the operation.

It will of course be appreciated that because the apparatus ispreferably enclosed, as within a casing as indicated at 75, suitableaccess doors and obesrvation windows or the like will be provided asneeded; and that an automatic temperature control system will preferablybe provided. For example, adjustable timers 80 to regulate the workpieceloading and freezing and unloading cycles may be provided; as well asadjustable controls for automatically regulating the relative length ofthe freezing cycle and the conveyor operating cycle and the blast cycle.Also, remote controls 80 for regulating the flow of carbon dioxide gasin the freezing operation, and for controlling the blasting machiner.p.m. and the mill conveyor speed, may be provided; as well asindicating devices for showing the temperatures at different parts ofthe apparatus.

It will of course be appreciated that selection ofthe abrasive media inany given case will depend upon the nature of the job to be done.Selection may be made from a wide variety of abrasive media such assteel shot, aluminum shot, soft grit, and the like. Whereas the abrasivemedia is shown herein as being projected into the blast chamber by meansof airless type blast machine, it is to be understood that any othersuitable arrangement may be employed, such as for example by entrainmentof the abrasive into and projection thereof by a sub-ambient temperaturegas or air stream discharging into the blast chamber. By virtue of themethod and apparatus of the present invention the technique offreeze-deflashing of rubber parts may be greatly expanded and adaptedwith various changes may be made therein without departing from thespirit of the invention or the scope of the following claims.

I claim:

1. A method for deflashing or trimming molded rubber parts, said methodcomprising freezing the flash portions of said parts to a condition ofembrittlement, and then subjecting the parts to an airless abrasivemedia blast operation from directions constantly varying angularly withrespect to the parts, collecting refuse from the operation comprising amixture of detached rubber flash debris and spent blast media,separating said refuse and segregating therefrom the reusable blastmedia and returning the latter to the operation for reuse.

2. An apparatus for definning or deflashing or trimming molded rubberparts or the like, said apparatus including a housing and means forprojecting an airless stream of blast media particles into said housing,means for supporting a plurality of workpieces interiorly of saidhousing while continuously turning them to present different facetsthereof to the blast media projection stream, means for reducing thetemperature of the workpieces so that the relatively thin portionsthereof become embrittled, means collecting from the operation a refusecomprising a mixture of removed rubber parts and spent media, meansseparating from said mixture the reusable portion of the blast mediaincluded therein and returning the same again to said blast projectionmachine, a dust collector having an inlet in communication with ahousing enclosing the blasting operation and the separation operation,and gate means regulating recirculation of the cooled air through theblasting housing.

3. A method for defiashing or trimming molded rubber parts, said methodcomprising freezing the flash portions of said parts to a condition ofembrittlement, and then subjecting the parts to an airless abrasivemedia blast, collecting refuse from the operation comprising a mixtureof detached rubber flash debris and spent blast media, separating saidrefuse and segregating therefrom the reusable blast media and returningthe latter to the operation for reuse.

4. An apparatus for definning or deflashing or trimming molded rubberparts or the like, said apparatus including a housing and means forprojecting an airless stream of blast media particles into said housing,means for supporting a plurality of workpieces interiorly of saidhousing, means for reducing the temperature of the workpieces so thatthe relatively thin portions thereof become embrittled, means collectingfrom the operation a refuse comprising a mixture of removed rubber partsand spent media, means separating from said mixture the reusable portionof the blast media included therein and returning the same again to saidblast projection machine, and a dust collector having an inlet incommunication with a housing enclosing the blasting operation and theseparation operation.

5. A method for deflashing or trimming molded rubber parts, said methodcomprising freezing the flash portions of said parts to a condition ofembrittlement, and then subjecting the parts to an airless abrasivemedia blast op eration from directions constantly varying angularly withrespect to the parts.

6. An apparatus for definning or deflashing or trimming molded rubberparts or the like, said apparatus in cluding a housing and means forcentrifugally projecting an airless stream of blast media particles intosaid housing, means for supporting a plurality of workpieces interiorlyof said housing While continuously turning them to present differentfacets thereof to the blast media projection stream, and means forreducing the temperature of the workpieces so that the relatively thinportions thereof become embrittled.

7. A method for deflashing or trimming molded rubblast media andreturning the latter to the operation for reuse.

8. An apparatus for definning or deflashing or trimming molded rubberparts or the like, said apparatus including a housing and means forprojecting an airless stream of blast media particles into said housing,means for supporting a plurality of workpieces interiorly of saidhousing while continuously turning them to present different facetsthereof to the blast media projection stream, means for reducing thetemperature of the workpieces so that the relatively thin portionsthereof become embrittled, a dust collector having an inlet incommunication with a casing enclosing the blasting operation and theseparation operation, and gate means regulating recirculation of thecooled air through the blasting housing.

9. A method for deflashing or trimming molded rubber parts, said methodcomprising freezing the flash portions of said parts to a condition ofembrittlement, and then subjecting the parts to an airless barrage ofabrasive projectiles moving at velocities suflicient to sever the flashportions from the workpieces when in impact therewith, collecting refusefrom the operation comprising a mixture of detached rubber flash debrisand spent blast media, separating said refuse and segregating therefromthe reusable blast media and returning the latter to the operation forreuse.

10. An apparatus for definning or deflashing or trimming molded rubberparts or the like, said apparatus including a housing and means forprojecting an airless barrage of blast media particles into saidhousing, means for supporting a plurality of workpieces interiorly ofsaid housing while continuously turning them to present different facetsthereof to the blast media barrage, means for reducing the temperatureof the workpieces so that the relatively thin portions thereof becomeembrittled, means collecting from the operation a refuse comprising amixture of removed rubber parts and spent media, and means separatingfrom said mixture the reusable portion of the blast media includedtherein and returning the same again to said blast projection machine.

11. A method for deflashing or trimming molded rubber parts, said methodcomprising treating the flash portions of said parts to assume acondition of embrittlement, and then subjecting the parts to an airlessabrasive media barrage, collecting the refuse from the operation,separating said refuse and segregating therefrom the reusable blastmedia and returning the latter to the operation for reuse.

' 12. An apparatus for definning or deflashing or trimming molded rubberparts or the like, said apparatus including a housing and means forprojecting a barrage of blast media particles into said housing, meansfor supporting a plurality of workpieces interiorly of said housingwhile continuously turning them to present different facets thereof tothe blast media barrage, means for treating the workpieces so that therelatively thin portions thereof become embrittled, and means separatingfrom the refuse of the operation the reusable portion of the blast mediaincluded therein and returning the same again to said blast projectionmachine.

13. An apparatus for definning or deflashing or trimming molded rubberparts or the like, said apparatus including a housing and means forprojecting an airless stream of blast media particles into said housing,means for supporting a plurality of workpieces interiorly of saidhousing while continuously turning them to present different facetsthereof to the blast media projection stream, means for reducing thetemperature of the workpieces so that the relatively thin portionsthereof become embrittled, 'means collecting from the operation a refusecomprising a mixture of removed rubber parts and spent media, meansseparating from said mixture the reusable portion of the blast mediaincluded therein and returning the same again to said blast projectionmachine, a dust collector having an inlet in communication with ahousing enclosing the blasting operation and the separation operation,gate means regulating recirculation of the cooled air through theblasting housing, a casing enclosing the housing and in which the meansfor reducing the temperature of the wlorkpieces comprises arefrigeration means and means communicating the refrigeration means withthe interior of the housing and the casing for the: introduction ofrefrigeration therein, and which includes means for feeding theworkpieces to the housing and means for delivery of the workpieces fromthe housing, dnd control and variable drive means for regulating thetime and sequence of the operations of the apparatus including thefeeding, delivery, refrigeration and blast cycles.

References Cited in the file of this patent or the original patentUNITED STATES PATENTS

